Conventional locks, such as padlocks employing U-shaped shackles, are extremely popular. One reason for their popularity is the ease and convenience of their attachment to, and fit with, the hasps and other attachment mechanisms or devices with which they are used to provide for the unlatching and opening of a secured assembly of elements.
The locks most frequently in use today rely on a single locking mechanism, most typically being operated by a key. Other locks rely on keyless locking mechanisms, such as combination locks. Notwithstanding, there are applications that require multiple function locks combining both key and combination functions. Multiple function locks typically allow for the opening of the lock by one mechanism independent of the other. This function is known as independent dual custody. A second embodiment requires both mechanisms to function in order to open the lock. This function is known as dependent dual custody.
Today, security concerns, particularly air travel safety mandate that the appropriate authority have access to checked luggage. Many travelers secure their luggage with locks intended for their personal access only. In the absence of the necessary key or combination the authorized security personnel may be required to remove these locks destructively.
Different solutions to the dual custody issues are available. The primary function is the locking of the heel of the shackle and the most popular means is a wheel combination mechanism. This device permits the owner to manipulate the wheels to the correct combination, lift the unlocked shackle from the toe-retaining chamber and rotate the shackle to permit the padlock to be removed from the attachment element. The second means to open the padlock is at the toe and may be by disengagement of the shackle from the toe-retaining chamber by the rotation and/or linear motion of the chamber to provide for the necessary movement of the shackle.
The travel luggage applications involve the security authorities. In the United States this is the Transportation Security Administration (TSA). This authority may cause any installed lock to be removed when deemed appropriate. The key function embodiment represents the currently accepted means to provide the second authority the means to open the padlock.
This key device has proven to be burdensome on the TSA. The lock to be opened and the key required must be identified. The key must be found, inserted in the lock, and manipulated to the unlocked position. The shackle is then lifted from the toe-retaining chamber, rotated to the open position and removed to allow the luggage to be open for the required inspection. After inspection, the lock must be reapplied and locked using the key. During this inspection operation, the key ring is not available to the other inspectors. The air travel environment in the United States involves about 460 airports with more than 4000 inspection stations provided with a key ring of about seven keys, a 24 inch bolt cutter and a pair of side cutting electrician's pliers. The maintenance of teams of trained personnel is a challenge and a faster, simpler, more effective method of securing luggage is a priority for the TSA.